Don't accept non-json writes.

cbugg: close bug-432
Tool for batch compacting.

cbugg: close bug-481
Remove JSON benchmark.

We no longer parse this way, and jsonpointer has its own
benchmarking.
fix so tests can run

previous commit removed last reference to this import
see b8cb1f9aae074f293187758cf5893aed30e23d12
change from *string to interface{} for matched values
update TestPointers test case to work with interface{}
added 2 new reducers that work with objects

obj_keys returns all the keys of the matched objects in the group
obj_distinct_keys returns all the distinct keys of the matched objects in the group
fixing TestNilReducers that I broke accidentally
added reducer distinct

distinct works like identity, but removes duplicate values
if returned value is array or object it is omitted
if returned value is numeric it becomes a string
Configurable number of concurrent compaction workers.
Benchmark the stdlib RFC3339 to compare against mine
Cache fix from upstream API change.
Cleaned up query processing.
Minor aesthetic changes.
Don't need to close request bodies.
Don't log fast queries
Ignore Infs along with NaNs

Can't JSONate them.

cbugg: close bug-805
Add "c" reducer

cbugg: bug-838
Update tests for c reducer

cbugg: close bug-838
Added a limit to _all